升温过程对藻类复苏和群落演替的影响

采用模拟升温方法培养太湖的冬季底泥,培养温度从5.5~30℃设计为8个水平,在各温度水平显微观察藻类群落组成,计算比生长速率,同时采用荧光法分析光合色素的浓度变化.结果表明,绿藻和硅藻在9℃时开始复苏,蓝藻在12.5℃开始复苏.虽然蓝藻复苏较晚,但是蓝藻复苏后的比生长速率高于绿藻和硅藻.12.5℃以后,藻类群落主要由蓝藻、绿藻、硅藻组成.在12.5℃和16℃时绿藻占优势;蓝藻在19.5℃以后占优势.叶绿素a浓度在9℃和16℃均明显升高,而藻蓝素浓度仅在16℃时明显升高.光合色素浓度的升高与绿藻和硅藻的复苏同步进行,但滞后于蓝藻的复苏.

Effects of enhanced temperature on algae recruitment and phytoplankton community succession.

Effects of enhanced temperature on phytoplankton recruitment and phytoplankton community succession were analyzed by a simulation experiment. Winter sediment was collected from Taihu Lake and cultured in BG-11 medium. The incubation temperatures were enhanced from 5.5℃ to 30℃ with eight gradients, and each temperature level was kept for ten days. Microscopic morphological observation was applied to analyze algal specific growth rate (SGR) and phytoplankton community succession, meanwhile fluorescence analysis was performed to detect variations of photosynthetic pigment concentration. Recruitment of Chlorophytes and Diatoms was observed at 9℃, but that of Cyanobacteria was not evidently detected until 12.5℃. Recruitment of Cyanobacteria initiated later than Chlorophytes and Diatoms, but the specific growth rate of Cyanobacteria after recruitment was highest. Phytoplankton community was overwhelmingly composed of Cyanobacteria, Chlorophytes, and Diatoms when temperature exceeded 12.5℃. Moreover, Chlorophytes dominated phytoplankton community at 12.5℃ and 16℃, Cyanobacteria subsequently established dominance above 19.5℃. Concentration of chlorophyll a increased evidently at 9℃ and 16℃, while that of phycocyanin went up markedly only at 16℃. Pigment concentration increased with the recruitment of Chlorophytes and Diatoms synchronously, but lagged behind Cyanobacteria recruitment.